Blockchain technologies implement distributed ledgers on peer-to-peer networks. Data is stored securely using cryptography and various consent mechanisms are employed with a view to ensuring data stored in a block of the distributed ledger is accurate and reliable.
Blockchains provide a way to trace unique digital items without reliance on a third party. Blockchains breakdown when mapping to physical real-world items due to the requirement of having to trust some sort of the third party. As Satoshi mentions in his paper, reliance on a third party immediately destroys/diminishes the use of blockchain—despite current hype around “putting it on the blockchain”.